Steering Interzeolite Conversion with Alkali Metal Cations: Lithium Maximizes Al Proximity in SSZ-13 Zeolite Genesis

Zeolites have long been regarded as difficult to modify during synthesis, as their synthesis is governed by kinetic processes. Recent breakthroughs have made it possible to exert a certain degree of control over zeolite properties with more performant materials as a result. Here, we investigate the effects alkali cations have on high-silica FAU-toCHA interzeolite conversion (IZC) and on the resulting aluminum distributions. In this way, by using Li-cations in conjunction with an organic structure directing agent, the first route to a "fully paired" (divalent cation capacity, Co2+/Al = 0.48) high-silica SSZ-13 zeolite is demonstrated. Lithium shows great potential in steering IZC synthesis as it speeds up crystallization, and evidence was gathered in favor of a more elaborate mechanism of IZC in which dissolved Al-rich oligomers crash out of solution first and possibly spark nucleation. These findings help in gaining insights into a more general theory on zeolite nucleation in heterogeneous environments such as IZC. Furthermore, the "fully paired" sample has great potential for ion-exchanged zeolite catalysis or in adsorbents.